Theses and Dissertations

Date of Award


Document Type


Degree Name

Master of Science (MS)



First Advisor

Dr. Rupesh Kariyat

Second Advisor

Dr. Lekshmi Sasidharan

Third Advisor

Dr. Bradley Christoffersen


Chapter 1: This chapter provides an overview of insect herbivore impacts on plants and plant defense mechanisms to combat them. I particularly focused on physical and chemical defenses in the broader sense.

Chapter 2: This chapter describes the experiments that showed the effects of extracts from Aloe barbadensis on the growth and development of tobacco hornworm (Manduca sexta) and fall armyworm (Spodoptera frugiperda), model herbivores used to understand herbivore growth and plant defenses. This study shows that extracts from the Aloe differentially affected the growth and development of M. sexta and S. frugiperda. This chapter also gives insight on various growth and development traits used to accomplish these findings.

Chapter 3: This chapter is focused on discussing the role of these Aloe extracts in the growth of fall army worm (Spodoptera frugiperda) and tobacco hornworm (Manduca sexta) and wax content of A. barbadensis. In this study I show that the extracts, while had differential effects, on some extracts the caterpillars performed better during the larval and pupal stages, while others were neutral or inhibitory. I also shed light on the wax content and the effect it had on the feeding behaavior of S. frugiperda. This chapter will also show scanning electron microscopy images of Aloe barbadensis leaf surface and wax.

Chapter 4: This chapter highlights conclusions and possible future works for identifying the Aloe barbadensis defense phenotype. Our results shed light into the possible reasons why Aloe barbadensis is not predated on much by insect herbivores and defenses that deter them. Secondary metabolites paired with surface wax possibly prevents Aloe barbadensis from sustaining heavy insect herbivore damage.


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